1. Field of the Invention
The present invention relates generally to thermistor holders and more particularly to a thermistor holder for skin-temperature measurements.
2. Description of the Prior Art
It is often necessary to measure the skin temperature of humans and animals to ascertain the effects on body temperatures resulting from the use of various types of drugs, exposures to selected environments, and many other situations.
In the past a number of different devices have been used for coupling temperature measuring electronic devices to humans and animals for sensing skin temperature. For example, a thermocouple holding button is disclosed in U.S. Pat. No. 3,464,864 to Rentz. The device disclosed in this patent consists essentially of a circular base having a thermocouple secured to one surface thereof, with a neck portion surmounted by a head formed integrally with the opposite surface thereof to permit a fastening device, such as an elastic band, to be coupled to the holding member. This device presses the thermocouple into the skin according to the force of the elastic band used to secure the holding member in place. Furthermore, no air circulation is permitted beneath the holding member so that the skin temperature in this region may be increased somewhat above normal, and sweat may form around the thermocouple member without the possibility of evaporation by normal air circulation.
A different type of surface contacting thermocouple holder is disclosed in U.S. Pat. No. 3,573,993 to Senbokuya. The device disclosed in this reference includes a thin band-like thermocouple member bent into a U-shape configuration and mounted to a pair of auxiliary springs which are in turn rigidly fastened to a fitting implement or support member. The device disclosed in this patent is complicated and delicate in its manufacture due to the use of various exposed spring members and is not easily fastened to a skin surface in view of the relative instability created by the particular use of the band-like thermocouple and auxiliary supporting springs. Thus, the apparatus disclosed in this patent is impractical for use in continuously monitoring skin temperatures, particularly during physical exercise, in view of the difficulties created in securing it in place and in view of its delicate structural configuration.
Another type of conventional mounting apparatus for skin temperature measurement is disclosed in U.S. Pat. No. 3,258,969 to Poirier wherein a conventional wrist-strap is used to secure a diaphragm shielded thermocouple in place on the arm of a wearer. Again, this device lacks flexibility in permitting separate adjustment of the securing means and the tension of the thermocouple against the skin and also inhibits the circulation of air over the surface of the skin in the region of the thermocouple.
The devices described above illustrate deficiencies in previously known apparatuses for holding skin temperature sensing units in place. Generally, they do not permit adequate air circulation over the surface of the skin in the region of the temperature sensing device, thus permitting the skin temperature to increase above its normal value, rendering measurements unreliable. Furthermore, the lack of air circulation can cause localized accumulations of sweat in the area of the electronic sensing device which can in turn result in corrosion of the device or its supporting members. Holding devices of the type described also generally lack the ability to separately adjust the restraining force for holding the members in place and the biasing force holding the temperature sensitive element into contact with the skin. Since skin temperature is directly related to the depth the sensor is pressed into the skin, it is often desirable to secure a holding member in place with a relatively large force and yet to press the thermalsensing member into engagement with the surface of the skin with a small force in order to prevent errors in temperature measurement. Accordingly, separate adjustment of these two forces is desirable.